Thinking about making my own duel feed system

I have a mag fed mkv that I can buy a hopper kit adapter here all I think I need to do is drill a hole install a detent on the other side of the marker and figure out how to block off what ever feed system I am not using. Any ideas?

I want to do the same thing with my mkpII. I want a qloader under the barrel so it looks like a grenade launcher and doesnt take from the realistic look of the gun and also not having a hopper on top is a huge plus in milsim paintball. Ive been struggling with the same dilema though of switching from the mag with first strikes in it to the qloader and paintballs

Another thing i was thinking of is just making a big box mag. So instead of trying to flip a switch for paintballs i just pull my mag out and throw on my box mag. A little more cumbersome to have strapped to your best but i think easier